The present invention relates to an electromechanical brake actuator for a rail vehicle brake comprising an actuator housing as well as electronic components, such as power electronics, control electronics or an electronic sensor system. At least some of the electronic components are accommodated in a separate electronic system housing which is detachably connected with the actuator housing. A brake actuator of this type is known, for example, from U.S. Pat. No. 5,692,586.
Currently, three wheel brake systems are essentially used in the rail vehicle field: Pneumatic or electropneumatic brake systems, hydraulic or electrohydraulic brake systems as well as mechanical or electromechanical brake systems. A wheel brake system may be constructed as an active or passive brake system, depending on whether the force of a brake actuator has to be applied for braking (active brake system) or for releasing the brake (passive brake system). In the event of operating disturbances, in the case of pneumatic systems, an energy accumulation takes place in compressed-air reservoirs; in the case of hydraulic systems, this energy accumulation takes place in hydraulic reservoirs; and, in the case of electromechanical systems, it takes place in the form of pre-loaded springs.
In the case of electromechanical brake actuators, an electric-motor drive is used as the service brake device, which can be controlled by control or power electronics to carry out slip-controlled or load-corrected brakings. When the brake actuator, together with the electronic components assigned to it, is to be fastened as an integrated brake module to the bogie or truck of a rail car, the problem arises that shock or vibration stress is caused, for example, by rail joints or switching shocks that may result in damage to the electronic components. Furthermore, particularly at high ambient temperatures, the electronic components may be subjected to a temperature-caused stress which leads to disturbances or to total failure.
The present invention further develops an electromechanical brake actuator of the initially mentioned type such that its electronic or electrical components have a greater reliability and a longer service life.
Thus, the present invention relates to an electromechanical brake actuator for a rail vehicle brake comprising: an actuator housing having a flange; electronic components; an electronic system housing having a flange detachably connected with the actuator housing, and at least some of the electronic components being in the electronic system housing; at least one vibration damping element of the detachable connection arranged between a flange of the actuator housing and a flange of the electronic housing; and a clearance existing between the electronic system housing and the actuator housing.
As a result of the flexible and vibration-damping element or flange connection between the electronic system housing and the actuator housing, the electronic components are uncoupled with respect to vibrations from the structure born noise of the actuator housing. In particular, the natural frequencies of the electronic unit are thereby displaced toward lower values, whereby higher-frequency excitations can no longer cause sympathetic vibrations. Furthermore, lower vibration amplitudes are obtained because of the energy loss in the damping elements.
As a result of the fact that, with the exception of the flange connection, clearance exists between the electronic system housing and the actuator housing, the presence of an insulating air layer or of a cooling air flow is permitted between the actuator housing heated by the operation of the electric drive and the electronic system housing. That permits the thermal stress acting upon the electronic components to be reduced.
The vibration-damping element or devices are preferably formed by a rubber ring which is arranged between the flange of the actuator housing and the flange of the electronic system housing. As a result, the rubber ring is situated in the flux or transmission of force between the actuator housing and the electronic system housing and vibrationally uncouples the latter from the actuator housing.
According to a preferred embodiment of the present invention, at least some of the electronic components are arranged on at least one printed circuit board which, inside the electronic system housing, is accommodated by at least one other vibration-damping element or device. This results in an additional vibration uncoupling of the electronic system components from the structure-borne sound guiding actuator housing or also from the electronic system housing.
A plug, which is assigned to the electronic system housing or to the actuator housing or a bushing assigned to the electronic system housing or the actuator housing is fastened to the actuator housing or to the electronic system housing, also in a vibration-damped manner. As a result, no stiff vibration-transmitting bridges can be created in the plug/bushing area.
Other aspects and novel features of the present invention will become apparent from the following detail description of the invention when considered in conjunction with the accompanying drawings.